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71.
Magnetic resonance imaging (MRI) is now a recognized method of imaging the breast. Unfortunately, there is lack of standardization in the MRI terminology used to characterize the appearance of breast lesions. Moreover, cases of mixed histologies are often imaged. We retrospectively identified cases of pure high-grade ductal carcinoma in situ (DCIS) using the recently introduced breast MRI lexicon and characterized the lesions in order to try and identify features that might distinguish high-grade DCIS from invasive disease. Five-year review of our institution's database revealed 637 patients underwent gadolinium-enhanced breast MRI examination. Twenty patients had histologically proven pure high-grade DCIS. After excluding patients with previous chemotherapy or inadequate MRI examination, 13 patients were analyzed and compared to the 13 most recent cases of pure invasive breast carcinoma. The morphological and dynamic features were then compared. High-grade DCIS cases were significantly more likely to show focal branching pattern (P=.03) and to have an irregular contour (P=.03), compared with invasive disease. Although of marginal statistical significance, DCIS lesions are more likely to have a lower morphological score than invasive carcinoma (P=.06), whilst the latter is more likely to show ring enhancement (P=.07). Use of breast MRI for staging at our institution shows that pure DCIS and pure invasive cancers are both rare entities. Despite the relatively limited numbers, we identified features that would help to differentiate high-grade DCIS from invasive carcinoma on MRI. 相似文献
72.
[reaction: see text] First examples of aromatic core-modified twisted heptapyrrolic systems with six meso links have been obtained via a general [3 + 4] acid-catalyzed condensation method. Despite the twisted conformation, these heptaphyrins exhibit aromaticity in solution, unlike most of the all-aza analogues. 相似文献
73.
Sankar J Rath H PrabhuRaja V Chandrashekar TK Vittal JJ 《The Journal of organic chemistry》2004,69(15):5135-5138
Three new methods for syntheses of modified oxa corroles bearing one meso free carbon in reasonably good yields are reported. The formation of the meso carbon bridge and the direct pyrrole-pyrrole linkage occur in a single step by a simple condensation and coupling with TFA as a catalyst with appropriate precursors. The reactions are optimized with different conditions by varying the meso substituents, acid catalyst concentration, and the nature of the solvent to afford corroles in good yields. 相似文献
74.
Thomas JM Raja R Johnson BF O'Connell TJ Sankar G Khimyak T 《Chemical communications (Cambridge, England)》2003,(10):1126-1127
Adipic acid (2) production currently entails use and generation of environmentally harmful materials: an efficient catalyst, consisting of nanoparticles of Ru10Pt2 anchored within the pores of mesoporous silica, facilitates the production of (2) by hydrogenating muconic acid, that may be derived biocatalytically from D-glucose. 相似文献
75.
76.
77.
Mal SS Nsouli NH Dickman MH Kortz U 《Dalton transactions (Cambridge, England : 2003)》2007,(25):2627-2630
Reaction of [Ru(p-cymene)Cl2]2 with [H7P8W48O184]33- (P8W48) in aqueous acidic medium results in the organometallic derivative [{K(H2O)}3{Ru(p-cymene)(H2O)}4P8W49O186(H2O)2]27- (1); in addition to the four {Ru(p-cymene)(H2O)} units, an unusual WO6 group with four equatorial, terminal ligands is also grafted to the crown-shaped P8W48 precursor. 相似文献
78.
Deepak Chopra T. P. Mohan B. Vishalakshi T. N. Guru Row 《Acta Crystallographica. Section C, Structural Chemistry》2006,62(9):o540-o543
The crystal structures of the title compounds, viz. C24H14F2N2O2, (I), and C25H17FN2O2, (II), respectively, have been determined in order to unravel the role of an ordered F atom in generating stable supramolecular assemblies. On changing the substitution from fluorine to a methyl group, C—H⋯F interactions are replaced by C—H⋯π interactions, revealing the importance of such weak interactions when present alongside N—H⋯O and C—H⋯O hydrogen bonds. The dihedral angle between the planes of the 4‐fluorophenyl ring and the pyridine ring is 26.8 (1)° in (I), while that between the planes of the 4‐methylphenyl and pyridine rings is 29.5 (1)° in (II). 相似文献
79.
A. Lakshmi Narayana M. Dhananjaya N. Guru Prakash O. M. Hussain C. M. Julien 《Ionics》2017,23(12):3419-3428
Nanocrystalline Li2TiO3 was successfully synthesized using solid-state reaction method. The microstructural and electrochemical properties of the prepared material are systematically characterized. The X-ray diffraction pattern of the prepared material exhibits predominant (002) orientation related to the monoclinic structure with C2/c space group. HRTEM images and SAED analysis reveal the well-developed nanostructured particles with average size of ~40 nm. The electrochemical properties of the prepared sample are carried out using cyclic voltammetry (CV) and chronopotentiometry (CP) using Pt//Li2TiO3 cell in 1 mol L?1 Li2SO4 aqueous electrolyte. The Li2TiO3 electrode exhibits a specific discharge capacity of 122 mAh g?1; it can be used as anode in Li battery within the potential window 0.0–1.0 V, while investigated as a supercapacitor electrode, it delivers a specific capacitance of 317 F g?1 at a current density of 1 mA g?1 within the potential range ?0.4 to +0.4 V. The demonstration of both anodic and supercapacitor behavior concludes that the nanocrystalline Li2TiO3 is a suitable electrode material for supercapattery application. 相似文献
80.
Gómez-Hortigüela L Corà F Sankar G Zicovich-Wilson CM Catlow CR 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(46):13638-13645
In this work we apply state-of-the-art electronic-structure-based computational methods based on hybrid-exchange density functional theory to study the mechanism of the aerobic oxidation of hydrocarbons catalysed by Mn-doped nanoporous aluminophosphates (Mn-AlPOs). We compare our results with available experimental data. We show that the catalytic efficiency of Mn-AlPOs in oxidation reactions is intrinsically linked to 1) the Mn redox activity, in particular between 2+ and 3+ oxidation states, and 2) the coordinative insaturation of tetrahedral Mn embedded in AlPO frameworks, which facilitates the reaction by stabilising oxo-type radicals through the formation of Mn complexes. Our mechanism demonstrates the crucial role of both Mn(III) and Mn(II) in the reaction mechanism: Mn(III) sites undergo an initial reaction cycle that leads to the production of the alkyl hydroperoxide intermediate, which can only be transformed into the oxidative products (alcohol, aldehyde and acid) by Mn(II). A preactivation step is required to yield the reduced Mn(II) sites able to decompose the hydroperoxide intermediates; this step takes place through a transformation of the hydrocarbon into the corresponding peroxo-derivative, stabilised by forming a complex with Mn(III) and yielding at the same time reduced Mn(II) sites. Both species enter a subsequent propagation cycle in which Mn(II) catalyses the dissociation of the hydroperoxide that proceeds until the formation of the oxidative products by two parallel pathways, through alkoxy- or hydroxy-radical-like intermediates, whilst the Mn(III)-peroxo complex enables further production of the hydroperoxide intermediate. 相似文献